The present invention is directed to detonators, and to an improved detonator structure and method of making the same whereby improved performance and shock resistance are achieved.
A problem in this art is that the walls of a detonator cylinder become contaminated with the primary explosive when loading the primary explosive into the detonator cylinder, also known as the casing. This is a problem since detonator walls contaminated with the primary explosive may result in several different kinds of failure modes. An additional problem is that once the primary charge is loaded, the shape of the charge has been determined by the cylinder dimensions on three sides of the loaded primary charge. The remaining dimension has largely been ignored, thereby ignoring the optimum shape for detonating purposes.
This art knows that removing the primary charge contaminant from the sides of the detonator cylinder walls provides a more reliable detonator. This has been addressed by what those skilled in this art term a "wiper ring." The wiper ring concept is disclosed in U.S. Pat. No. 4,821,646 issued Apr. 18, 1989, incorporated herein by reference. Therein disclosed is a means of wiping the cylinder wall to provide a cleaner cylinder wall surface. There is no mention of shaping the primary charge.